Panhard bars work to:
- Keep the rear axle from moving side to side
- Keep handling consistent
- Reduce chassis flex/twist
- Eliminate rear-steer
- Help with cornering
What many would argue is the most important function of the panhard bar is it keeps the rear axle from moving side to side. Without the panhard bar keeping the rear axle from making lateral movements, you would suffer from rear-steer, which basically means your wheels shift and steer you towards an undesired path. For example, A 1999-2004 Mustang's rear axle can move up to 2 inches side-to-side under harsh conditions.
With the configuration of panhard bars bracing your chassis laterally in the rear, chassis flex from going around a turn is greatly reduced. Panhard bars keep handling predictable and consistent which is why aftermarket ones will greatly improve your cornering limits. Some additional benefits to expect, aside from stable cornering and overall handling predictability, are lowering the vehicle’s rear roll center. This prevents the inside of the rear tires to lift off the ground when you go around corners, further giving you more stability.
Panhard bars are a required upgrade when you lower your Mustang as you will need to adjust the rear axle. Panhard bars are available in both adjustable and non-adjustable varieties, with adjustable bars being more ideal for lowered cars and competitive builds.
Another alternative to panhard bars is a watts link setup which replaces the panhard bar, taking on all of the same responsibilities while also helping to prevent vertical movement. Watts link suspension systems help to make an SRA equipped Mustang feel more like an IRS equipped one.